Depending on the processed material from each drill must be properly sharpened. To verify the correct angle will help a specially prepared square plate of copper or aluminium with a thickness of 1 mm.
To become operational protractor enough to cut it cut, as shown in the picture: a large cutout at an angle of 120 degrees, the other half is 60 degrees and the surviving corner of a square is 90.
Recommend to read
SHELF-RING
Indeed, such an unusual O-shaped shelves will not find in stores. It can be made only on their own, because it is made from... old table. Yes, the same round, which was an obstacle in...
ALLY HAMMER
it would be easier to bend the nail! And if you need more than one... dozen! Well-known methods in such cases is not justified: the tedious, time-consuming. The proposed device is...